1. Field of the Invention
The present invention relates to a high-frequency knife for incising a living body tissue or the like.
This application is a continuation claiming priority on the basis of Japanese Patent Application No. 2012/200649 filed in Japan on Sep. 12, 2012 and based on PCT/JP2013/073690 filed on Sep. 3, 2013. The contents of both the Japanese Patent Application and the PCT Application are incorporated herein by reference.
2. Background Art
In the related art, the treatment of endoscopically incising living body tissues, such as a mucous membrane, is performed. In order to perform such incision treatment, for example, a high-frequency knife described in Japanese Patent No. 4455002 is known.
In this high-frequency knife, a stopper member is coupled to a tip of a sheath. A ring-like insulated tip (supporting member) is disposed on a distal end side of the stopper member. A proximal end portion of a knife portion (electrode portion) is connected to a distal end portion of an operating wire, which is inserted through the inside of the sheath, via a stopper receiving portion. This knife portion includes an electrode having a proximal end portion connected to the stopper receiving portion, and an electrical insulator portion (a larger-diameter portion) provided at a distal end portion of the electrode.
The electrode includes a first electrode portion (a rod-shaped electrode or a tubular electrode) that is formed as a small diameter rod with a constant diameter, and a second electrode portion (auxiliary electrode) that is provided at a distal end portion of the first electrode portion, and radially extends in the radial direction of the first electrode portion. The electrode is formed from a conductive material, such as a titanium alloy.
In the high-frequency knife configured in this way, if the operating wire is moved (pulled back) to the proximal end side with respect to the sheath, the second electrode portion abuts against the insulated tip. This is a state where the knife portion is not used. On the other hand, if the operating wire is moved (pushed in) to the distal end side with respect to the sheath, the second electrode portion advances to separate from the distal end of the sheath. This state is a state where the knife portion is used, such as a case where a tissue, such as a mucous membrane is excised by applying an electric current to the knife portion.
When the excision of the mucous membrane is performed using the high-frequency knife, a saline is injected into a submucosal layer of a lesioned mucous membrane portion to be excised, using an injection needle, and the lesioned mucous membrane portion is made to bulge. A counter electrode plate is worn by a patient. The knife portion of the high-frequency knife is inserted into a hole made around the lesioned mucous membrane portion, in a state where the second electrode portion is separated from the distal end of the sheath. If the knife portion is moved in a transverse direction (a radial direction orthogonal to the direction of an axis of the sheath) while supplying a high frequency current to the electrode of the knife portion, the mucous membrane that comes into contact with the first electrode portion is incised.
The knife portion to which the high frequency current is supplied has a high temperature of, for example, hundreds of degrees Celsius.
When the mucous membrane is excised, blood may flow out of an excised portion or the like. The study for cleansing this blood, which has flowed out, with the aforementioned high-frequency knife is also performed. That is, a gap is formed between the insulated tip and the operating wire, and a guide hole is formed in the electrical insulator portion so as to extend in the axis direction. This guide hole is formed between the second electrode portions that are adjacent to each other in the radial direction when viewed in the axis direction.
Then, if the saline is made to flow into a conduit line of the sheath in a state where the operating wire is pulled back and the second electrode portions are made to abut against the insulated tip, the saline is jetted to the front of the electrical insulator portion through the aforementioned gap and guide hole.